In general, in a wireless communication system, various multimedia services such as video, music, and game playing are provided. In order to smoothly provide a multimedia service, a high speed data transmission rate for an enormous amount of multimedia data should be ensured. Thus, research for improving performance of an antenna apparatus in a communication terminal has been performed. This is because in a communication terminal, an antenna apparatus substantially transmits and receives data for a multimedia service. At the present, in a wireless communication system, as an antenna apparatus mounted in a communication terminal, a MIMO antenna apparatus is suggested. The MIMO antenna apparatus includes a plurality of antenna devices. In such a MIMO antenna apparatus, by transmitting and receiving a signal in a predetermined frequency band through antenna devices, data can be transmitted in a high speed.
However, when operating such a MIMO antenna apparatus, electromagnetic coupling occurs between antenna devices. This is because when decreasing a size of a MIMO antenna apparatus in order to decrease a size of a communication terminal, a performance of a wireless communication system is deteriorated. Therefore, a method of suppressing electromagnetic coupling between antenna devices in the MIMO antenna apparatus is needed.